Corynebacterium parvum treatment of P388 tumor-bearing mice. II. Lysosomal enzyme levels associated with P388 tumor cells.

The number of tumor cells recovered form the peritoneal cavity of mice administered Corynebacterium parvum (C. parvum), Bacillus Calmette-Guérin (BCG) or saline 2 days before tumor implant was assessed on days 1, 2, 3, 5 and 7 following the intraperitoneal (ip) administration of 10(6) P388 leukemic cells. C. parvum-treated mice manifested a significant decrease in the number of tumor cells recovered from the peritoneal cavity on days 3-7, while BCG-treated mice had tumor cell yields comparable to saline control values. Lysosomal enzyme activity (acid phosphatase and beta-glucuronidase) in the nonadherent lavage cell population, which comprised tumor cells and host cells obtained form tumor-bearing animals, closely reflected the changes observed in tumor cell numbers and was initially assumed to be associated with tumor cells. When lysosomal enzyme activity was expressed as a function of the number of tumor cells or cellular protein, an enhanced activity following C. parvum treatment but not following BCG treatment was demonstrated. Enzyme activity associated with tumor cells was maximal 2 days prior to the profound depression in tumor cell maximal 2 days prior to the profound depression in tumor cell yield and may be associated with tumor cell killing. It is concluded that a correlation may exist between lysosomal enzyme activity, tumor cell numbers and the protective effect of the immunostimulant C. parvum. Whether the correlation is direct or indirect remains to be resolved.